Stuart became convinced the tiny white dot near the center of this photo represented the flash created by an explosion on the lunar surface.
Dr. Leon Stuart
hide caption

itoggle caption
Dr. Leon Stuart

Using images of the lunar surface snapped by the Clementine space probe, Buratti spotted a mile-wide crater -- the site of Stuart's Event.
NASA
hide caption

itoggle caption
NASA

Back in the 12th century, monks in England claimed they saw a spectacular eruption of fire and hot coals on the crescent moon. Others have since made similar claims about mysterious lunar flashes. Professional space scientists have dismissed such amateur reports, saying there's no evidence the flashes related to anything happening to the moon itself. They say they may simply be meteors streaking past the moon. But now, a NASA researcher says at least one amateur astronomer was right. NPR's Vikki Valentine reports.

Dr. Leon Stuart was a physician in Tulsa, Okla., but his passion was stargazing. One night in November 1953, he was outside, toying around with a camera he had added to his telescope. By sheer chance, he captured what appeared to be a once-in-a-lifetime event: a photo of an explosion on the lunar surface.

"It looks like a bright star in the middle of the moon," says Bonnie Buratti, a NASA planetary researcher who studies the moon for fun.

Buratti says Stuart was convinced he had witnessed an asteroid crashing into the moon. He published his photo and his theory in a 1956 issue of The Strolling Astronomer, an amateur astronomy newsletter. But professional researchers dismissed Stuart's idea, suggesting that what he actually saw was just a meteoroid burning up in the Earth's atmosphere.

Stuart didn't change his mind. When he died in 1968, he was still convinced he had caught a lunar collision on camera. The incident was known as "Stuart's Event" in astronomy circles.

When Bonnie Buratti came across the photo decades later, she thought Stuart's idea of an asteroid crash was worth a second look.

"The first thing I thought was, 'Well, if this really were the crash of a comet or an asteroid, there would have to be a crater, and wouldn't it be neat if we could find the crater?'" Buratti says.

According to Stuart's photo and description, the asteroid would have been the size of an 18-wheeler. Buratti then calculated the crater's location and how big it would be. She and a graduate student searched through thousands of images of the scarred lunar surface. Finally, they came across an image of a mile-wide crater snapped by Clementine, a NASA space probe that took 2 million photos of the moon in the mid-1990s.

"It was a eureka moment that a scientist can only hope to experience once or twice in their lifetime," says Buratti, who published her work this year in the space journal Icarus.

Paul Lowman, a lunar geologist with NASA, has seen Buratti's study and agrees that Stuart was right — the doctor had indeed witnessed a major asteroid impact.

"I really respect amateur astronomers, and Stuart was a good one," Lowman says. "The amazing thing is that he was lucky enough to photograph it."

Some astronomers still aren't convinced. They say the explosion Stuart described should have appeared as a much bigger fireball on the photograph. But Buratti says the fact that there's still more analysis to be done on Stuart's image shows how valuable the work of amateur astronomers is.

In the meantime, those in astronomy circles are now referring to Stuart's Event as "Stuart's Crater."